Casting apparatus



1944- R. G. WILSON 2,364,179

CASTING APPARATUS Filed Dec. 20, 1945 INVENTOR. Rai er! (vi/1077022 BYNa/wm 9; Emma ATTORNEYS Patented Dec. 5, 1944 l mmatlonpeceml er 2 o, ielas ri no. waste in it means; (all 22- 122lM inventi n relates'toiappar'a tus forcast- Iprovideany suitable engaging means, silchasing diamond core bits andhasfordts object the two or more inclinedholes. which? grippin provision of: an improvedlapparatus of thlscharmeans, such as tones or other"?extractmgftool; actor. The inventionailn'sjto provide. an im-* maybe inserted. l c v t proved apparatus ofthe type in which the dia- Theseand other novel features of theFinvenmonds are heldj imposition in a'mold by ,niean's' 1 tion willlbe letter.understood atten'cdnsidering of a vacuumanddnwhich the metaltoform the tthe following ;discusslonjtakenln conjunction diarhondf core bit ispoured overthediamonds; with 'theaccompanying"drawing, in which:-

The apparatusof the inventioncompri'ses '8. Fig. 'l'is aside'elevatlohar'view; with partsfln cup-shaped" .b I platejarrangedto'fbemounted l0 section, "ofapparatusl;embodyihg"the invention;onatable orthe like,acarbon;preferahligrapha and 1 f itejgmoljdsupported injspaced positionabovethe' i Fig. 2ii s a 'viewalong,Iine Z Jof Fig. 1? t base plate andf lan annulareledtricalfl ieating f 'Ifhe'apparatus illustrated "inthe drawing com member surrounding: the; mold.In an advan-' prises a table I on i which isijmoun'tedla cup]- tageousembodimentyof the I invention, the eleci-f 'shapedbaset plate Z formedojfiro'rl or steel which tricalheatingmemberissupported uponthe-base isconnected bypi p e atoaivaouum pump not? plate andfh'as' acircularcientrafopenlng'inwhich shown; "I'heivacdum appliedlitdthespacel abovethe mold' is supported,,'the base' yplate; heating the cup-shaped baseplate is controlled by means member and mold forminga closed space'which 1 of the quick action valve-5f andthe reIieffvalve issubjected. tointermittentvacuumf'lhe mold 201i Anyfsuitable type of [vacuum gage 1may is preferably of the usual type and comprises i be used to indicatethe amount; of vacuum andf an annular channel 'with' a rounded bottomfor a fijilter {may be connected to thepipe to re receiving the metal toform the bit, and a multil movjefparticles" oi metal from the vacuumsysplicity of small holesconnecting the channel with temi c r the closedspace in which the diamonds are held The base plate ispreferablycylindrical in shape by the vacuum during casting. The mold isin withan annular centering groove ID in which direct thermal contactwith the heating element theannularelectricalheating element II is sup land is heated to any desired temperature bepo te he phite mold IZ has adependin fore the metal is pouredinto the mold. cylindrical portionwhich fits snugly inside a cy- In order to provide abody of metal abovethe lindrical opening of the heating element and is bit to increase thepressure of the metal in the supported by the projecting shoulder 13.The mold and control the cooling of the bit, a metal 1 mold has anannular channel M with cylindrical it collar is mounted over the mold;to form the sides and a rounded bottom for receivin the outside wall ofa mold extension. The upper metal to form the bit, and a centralcylindrical P surface or the mold is cut out or otherwise formed 3:centering hole l5 for receivinga cylindrical X- to leavean annularshoulder for centering a ns on h m ic m l i e metal collar. one of theimportant features of i I h re ll m y h t p d inward y in an theinvention is a core of metal, for example lsuitable manner and may beconical, pyrami al, steel, which is supported over the center of the 1or the like, to facilitate its removal from the cast mold and in thecenter of the collar. The mold 40 metal; The surfaces of connectionbetween the c has a. central hole and the core a depending up-shapedbase plate, the electrical heating elepart which engages the'hole tocenter the core. ment, the graphi mold and the The core is a littlesmaller in outside diameter T sufficiently close that the elements'areheld in tha th m mete of t t and t 1. such contact that anysuitablevacuum of from, lar is sufficiently larger in insid diameterthan 4 S 2 n h s to 1 i h f Wa er may be created the core that anappreciable body of metal ex- 1111 the pa e c tends upward f omthe bitbetween the collar y In order to provide a ody of me l extending a d r jc an appreciable distance above the actual core bit,

The upper part of the core is tapered, for to apply pressure to themetalin the moldand to example conical or hemispherlcaLto facilitate itsprevent undue cooling of the metal, the metal removal from the body ofmetal above the bit. collar 20, preferably of iron orsteelpis placed inl The smaller diameter of the core than the inside supporting positionon an upper edge of the mold diameter of the bit facilitates removal ofthe and is centered by the projecting shoulder l3. core through theinside of the bit. For the pur- The inner diameter of the collar issomewhat less pose of pulling the core out of th body of metal, than theouter diameter of the bit but a a little temperature of around 750?larger than the inside diameter of the core. The core is preferably, 'atits point of maximum diameter, slightly smaller than the inside diameterof the bit and has engaging means such as the inclined holes 2| intowhich gripping means, such 1 as tongs or the like, may be inserted topull the i; core out of the bit and body of metal.

The annular channel M in the mold has a number of closelyspaced grooves24 and ribs 25 extending in the longitudinal direction. of the bit, anda multiplicity of small holes 26 radiating from the sides and therounded bottom portion of u 21 the annular channel wherein the diamondsare secured in position during casting by the vacuum in the space 4. Theribs 25 formch'annels in the bit to enable water through duringdrilling.

to be forced there- In forming a diamond core bit'inthe ahpara tus ofthe invention, the various elements of ap-v paratus are assembled in themanner shown in the drawing; The-' electricity is adjusted by means of arheostat'Knot shown) to provide the required amount of heat to heat themold l2 toa F. By meansof'the valves 5 and 6, the pressure inspaoe 4 isreduced to any desired pressure, say,around 12' inches of.

water; pressure, and the 'diamondsar'e placed in position, onej'in eachof the small holes. The molten metal toform the'bit, such as 'a cobalt,nickel, chromium steel alloy having, a Brinell hardness of around 450,is poured into the space between the core lland the. collar when at atemperature of around 2600' F. The metal flows intothe annular groove ofthe mold causing the diamonds to .bepartially embedded therein and fillsthe spacebetween the coreand thecollar, as shownin Fig. '1. 'This bodyof metal above'the bit increases the density of the bit and provides asufiicient reservoir of heat to preventundue cooling of the metal in thebit. After the metal is solidified, the collar is removed, the graphitemold broken away from the "bit, and the coreis pulled ready to be brazedor prongs which engage the holes 2|. By means of a carborundum saw orextending above the bit is cut off and the bit is otherwise attached toa bit shank.

I claim:

1. An improved apparatus for casting diamond core bits which comprises abase plate, a mold, means for supporting the mold on the base plate, anelectricalheating element in heat exchange contact with the exterior ofthe mold; a metal collar centered in and resting upon an upper por- 7tion of the mold, and a metal core centered in and resting upon an upperportion of the mold, said core being sufiiciently smaller in outsidediameter than the inside diameter of the collar that space is left foran appreciable body of metal above the core bit formed'in the mold, andmeans for removing the core from the body of metal.

2. An improved apparatus for casting diamond core bits whichcomprises abase plate, anfarinular electrical heating member supported on thejbaseplate, a graphite mold supported on the electrical heating member, meansfor creatinga vacuum in the spacebetween the mold, heating element andbase plate, an annular channel .in' the mold for receiving the metaltoform the bit, a multiplicity of small holes in the mold in whichdiamonds are held in position by the vacuum while the metal is beingcast in the annularchanneLa metalfcore centered in and supported upontheljm'old,

its removal and a maximum diameter where it engages themold' which isslightly smaller than the inside diameter off'the bit, and ametaljzollar,

ROBERT 1G. WILSON.

the like, the body of metal said 1 core having a tapered upper portionto' facilitate

